The present invention is related generally to a magnetron apparatus for coating substrate articles by sputtering, and more particularly, to an improved rotatable magnetron apparatus including a replaceable target structure. Additionally, the present invention is related to an improved method of replacing a target structure of the rotatable magnetron apparatus.
The coating of large area substrates, such as architectural glass, automobile windshields and the like, has been accomplished by a sputtering process that includes the use of a planar magnetron. Such coatings include multilayer solar control coatings that are widely used on commercial building windows. Because of the large surface area of the glass to be coated, the coating machinery is very large in scale.
More recently, a rotatable magnetron apparatus has been developed for such coating applications to overcome some of the problems known to inhere in the planar magnetron. A rotatable magnetron is described in U.S. Pat. No. 5,096,562, issued to Alex Boozenny and Josef T. Hoog on Mar. 17, 1992, the entire disclosure of which is incorporated herein by this reference.
Operation of the rotatable or rotating magnetron generally includes the rotation of a substantially cylindrical sputtering target in high vacuum about a stationary magnetic array, while providing appropriate fluid cooling. Thus, the rotating magnetron generally requires a rotational drive mechanism, bearings to permit target rotation about the magnetic array, and electrical and cooling conduits.
Because such rotational drive mechanism and conduits extend from an ambient environment into the vacuum chamber, the rotating magnetron further requires the use of vacuum seals around the rotational drive mechanism and the electrical and cooling conduits. While vacuum and rotary water seals have been used for this purpose, such seals have a tendency to develop leaks under conditions of high temperature and high mechanical loading.
In previous rotating magnetrons, removal and replacement of the target structure involves the removal, handling and replacement of the critical vacuum seals. While such handling exposes the seals to moisture and contaminants, the replacement of the seals further presents the opportunity for improper reassembly. Thus, the reassembly of these rotating magnetrons puts seal integrity, a critical aspect of effective sputtering, in question.
Additionally, the removal and replacement of the target structure in these rotating magnetrons is complicated and requires several hours. Such inefficient removal and replacement procedures result in large labor and production costs for less than optimum product throughput. Further, during such prolonged removal and replacement periods, the coating chamber is exposed to the ambient environment and thus, to moisture and contaminants. Such exposure adversely effects both product quality and yield. Thus, in the reassembly of these rotating magnetrons, unnecessary production costs are incurred, significant production time is lost, and product quality and yield are compromised.
Accordingly, it is an object of the present invention to provide an improved rotatable magnetron having an easily removable and replaceable target structure.
It is a further object of the present invention to provide a method for the efficient removal and replacement of the target structure in a rotatable magnetron.